The United Nations Security Council voted unanimously yesterday to dispatch military observers to Syria as at least nine people were killed in scattered violence that threatened the country's fragile ceasefire.

The heaviest fighting was reported in Homs where forces loyal to President Bashar al-Assad, pictured inset, shelled areas held by rebels, who returned fire with rocket-propelled grenades. In Aleppo, Syria's largest city, government forces were reported to have opened fire on mourners at a funeral. Meanwhile, opposition gunmen ambushed a car carrying soldiers in the southern province of Daraa. The tit-for-tat attacks came as the two sides traded allegations of violations of a UN-brokered truce, which formally took effect on Thursday.

The vote marked the first time since the conflict began more than a year ago that UN diplomats on the council had all agreed on a resolution. It called on both sides to immediately "cease all armed violence in all its forms". It also called on the Syrian government to implement the six-point peace plan drawn up by the international envoy Kofi Annan, including the withdrawal of troops and heavy weapons from cities and towns.

The resolution authorised the deployment of an advance team of up to 30 unarmed military observers to contact both sides and report on the ceasefire. The council said it immediately intends to establish a larger UN supervision mission after talks between Secretary General Ban Ki-moon and the Syrian government. Deployment of a larger force will be "subject to a sustained cessation of armed violence in all its forms by all parties".

A spokesman for Mr Annan, Ahmad Fawzi, has said that the envoy envisions a mission with about 250 observers. Russia and China vetoed two previous resolutions that would have condemned President Assad's government for its bloody crackdown on protesters and raised the threat of possible further action. The two countries argued that the resolutions were not balanced and didn't address the attacks by rebel fighters.

In the debate on the resolution adopted yesterday, Russia submitted a rival text to the US and Western-backed draft, and raised questions on Friday evening about the final draft. But Ambassador Vitaly Churkin told reporters before yesterday's vote that Moscow "was satisfied" and would vote yes.

The ceasefire is at the centre of Mr Annan's peace plan, which is aimed at ending more than a year of bloodshed that has killed at least 9,000 people, according to the UN, and to launch inclusive Syrian-led talks on the country's political future. Mr Annan called for the speedy deployment of UN monitors, and his spokesman told a news conference in Geneva on Friday that an advance team of "around 10 or 12" observers, which could quickly be increased to 30, was "standing by to board planes and to get themselves on the ground as soon as possible" once the Security Council approved their deployment.

William Hague, the Foreign Secretary, welcomed the decision. "This mission is a vital step in supporting the fragile ceasefire in Syria," he said in a statement.

Meanwhile, Germany is looking into a report that weapons bound for the Syrian regime were loaded on to a German-owned ship. Der Spiegel reported yesterday that the Atlantic Cruiser was halted in the Mediterranean after its owners were warned it was suspected of carrying Iranian military equipment to Tartus in Syria.

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